The invention relates to an electric reflector lamp provided with:
a rotationally symmetrical lamp vessel having an axis of symmetry and a greatest diameter transverse to said axis,
a neck-shaped first portion behind the greatest diameter, which portion carries a lamp cap provided with contacts,
a mirror-coated second portion which fluently merges into the first portion and extends towards the greatest diameter in a direction transverse to rather than longitudinally along the axis of symmetry, which second portion in axial cross-section is substantially curved according to a parabola branch having a focus, the axis of symmetry lying between the focus and the relevant parabola branch,
a mirror-coated third portion which merges fluently into the second portion and extends in a direction longitudinally along rather than transverse to the axis of symmetry, which third portion in axial cross-section is substantially curved according to a circular arc having a centre of curvature, the axis of symmetry lying between the centre of curvature and the relevant circular arc and the centre of curvature lying in a region between the focus of the parabola branch and the first lamp vessel portion,
opposite the neck-shaped first portion, a fourth portion adjoining the third portion,
a light source arranged inside the lamp vessel,
current supply conductors extending from the light source to the contacts at the lamp vessel.
Such a lamp is known from U.S. Pat. No. 4,803,394.
The lamp vessel of the known lamp has a shape which renders it suitable for being provided with various coatings in order to obtain a lamp which is suitable for one of various applications each time. An important application is that of a reflector lamp, which is obtained by providing the second and the third portion of the lamp vessel with a mirror coating. The object of this lamp is to provide a light beam with a high luminous flux and a high luminous intensity in the beam centre.
The lamp vessel of the known lamp was specifically designed for a helical incandescent body as the light source, which body is arranged transversely near the greatest diameter, bent around the axis of symmetry.